The energy cost for businesses continues to rise. The energy costs for businesses are significant especially in the industrial sector wherein hundreds or thousands of kilowatt hours of power may be used daily. These energy costs are generally fixed costs that are passed on to the consumer by increasing the cost of a manufactured product. In a global economy, many businesses have been required to find ways to cut product costs in order to successfully compete in the marketplace. Some businesses have implemented automation to reduce overhead costs. However, the increased amount of machinery used to automate a particular manufacturing has resulted in increased energy usage. Although energy usage and cost has become an increased concern for residential, commercial and industrial consumers, there have been few options to reduce this cost.
Electrical rate structures vary for commercial and industrial customers. Billing terminology and contract terms can be complex and are often misunderstood. When estimating power costs, it is important to understand the billing structure for a particular customer. Even the most complex electrical billing schemes have the same basic features. All customers pay an “Energy Charge” for electrical consumption or the amount of electricity used. Usage is calculated in kilowatt-hours (kWh). The cost for direct consumption is based on a kilowatt-hours charge, and may be adjusted seasonally. Other direct and indirect consumption charges such as the “Fuel Cost Adjustment”, the “Purchased Power Cost Recovery Factor”, and the “Cogeneration Power Cost” may not always appear on the monthly utility bill, or may, for simplicity, be incorporated into the overall cost for consumption. The time of day when consumption occurs may also influence utility costs. Some electric utilities divide total consumption into peak and off-peak components and charge accordingly. Peak supply hours for a utility generally occur between the hours of 8 a.m. and 9 p.m. and the cost of energy to consumers during this time may be nearly double the off-peak cost. Calculating energy charges is relatively straightforward. For example, a customer which consumes 6 kilowatts (6000 watts) of electricity for 8 hours would use 48 kWh (6 kW×8 hours). If the energy charge for electricity is $0.05 per kWh, the cost of energy to the customer is $2.40 (48 kWh×0.05=$2.40).
In addition to the basic energy charges to customers, most commercial and industrial customers pay a “Demand Charge” for the maximum rate that energy is used. This charge covers the costs associated with maintaining sufficient electrical facilities at all times to meet each customer's highest demand for energy. This charge is based on the average amount of electricity used by the customer in a defined period within the billing period. The demand charge is expressed as a dollar per kilowatt (kW) and is applied to the customer's maximum kW demand, or the highest electrical usage the customer demanded from the power system during the month. For large power consumers, the utility customarily installs a meter that measures the customer's instantaneous demands over each 15 minute interval throughout the monthly billing cycle and calculates the customer's demand charge based on the highest 15 minutes of power use during that billing cycle. Of course, the same concept may be applied using other time intervals and some power companies use a 30-minute interval or other interval. A customer who turns on a system that consumes 100 kW, runs it for 15 minutes, and then shuts it off consumes 25 kWh. Another customer turns on another system that consumes only 50 kW and runs it for 30 minutes also consumes 25 kWh; however, the first customer demanded 25 kWh at a rate of 100 kW per half hour and the second customer demanded 25 kWh at a rate of 50 kW per half hour over a longer period of time. The first customer's demand, or rate at which that customer requires the electric power to be delivered, was twice that of the second customer. While both customers are charged for 25 kWh of energy, the first customer is charged for 100 kW of demand, while the second is charged for only 50 kW of demand. As a result, the first customer ends up paying more for the consumption of 25 kWh than the second customer. This cost different exists because it costs the power company more to serve the higher-demand customer, since power companies must have more facilities in place to serve the higher demand at any given moment. The demand charge reflects this higher cost and provides an incentive for customers to manage their loads to lower their demand.
Demand charges can be particularly high for large plants that have negotiated special utility rate contracts. In many parts of the country, utility capacity is highly stressed and over the last ten years, savvy utility companies have offered “cost reductions” to contract purchasers that were based on holding demands constant and have a very high penalty for additional growth. In some contracts where the demand charges are very high, the energy charge is actually a negative value meaning that the utility will pay the consumer to burn more power. Of course, this is offset by the demand charge in the favor of the utility. A “Ratchet Clause” may be included by the utility to penalize an unusually high monthly peak demand by applying that demand to the rate structure for 12 months after it occurs. Additional demand charges may be applied when an industrial site experiences a low Power Factor. This occurs when equipment inefficiently converts supplied power to other uses.
Industrial consumers that utilize electric arc welders in an assembly process to manufacture products (e.g., automotive industry) typically require significant energy demands and incur significant energy costs. In these industries, hundreds or perhaps thousands of welders are employed to drive multiple aspects of an assembly process, wherein sophisticated controllers enable individual welders to operate within relevant portions of the process. In many of these processes, an automated system is used to control the power and/or waveforms supplied to the electrode, movements or travel of a welding tip during welding, electrode travel to other welding points, gas control to protect a molten weld pool from oxidation at elevated temperatures and provide ionized plasma for an arc, and other aspects such as arc stability to control the quality of the weld. These welding systems are often deployed over great distances in larger manufacturing environments and many times are spread across multiple manufacturing centers. Given the nature and requirements of modern and more complex manufacturing operations, welding system designers have begun interconnecting multiple welding machines together to control the operation of such welders. In the past, many conventional welding systems operate in individually controlled and somewhat isolated manufacturing locations in regard to the overall assembly process. Thus, controlling, maintaining, servicing and supplying multiple and isolated locations in large centers, and/or across the globe, became very challenging, time consuming and expensive. In addition, the energy consumption of these remotely located welders was typically unknown. Conventional welding systems often require engineers and designers to travel to a plurality of different welding locations to manually change, and/or modify, a current production process. This may involve modifying programs associated with the control aspects of each welder, for example. After modifications have occurred, individual welders may then be tested at each location to verify one particular portion of the overall process. When the overall assembly operation is finally underway; however, it may be discovered that some individual welders need to be “tuned” or modified in order to integrate with other welding systems contributing to the process. This may involve sending a systems engineer to each welding location in a large assembly operation to modify an individual portion of the process. Moreover, systems engineers may adjust a particular welder in an isolated manner without knowing if the latest adjustment suitably integrates into the overall assembly process. This is both time-consuming and expensive. Another challenge facing welding systems relates to service and maintenance. Welders are often maintained and serviced according to procedures implemented by operators of the welding systems. Although some operators may adequately service and maintain these systems, quality of the service and maintenance is often up to the training and competence of the individual operator. Thus, a large collection of well-maintained welders servicing an overall assembly process may be at the mercy of another welding system that is not properly serviced or maintained. This may cause the process to stop or be disrupted during service outages relating to a poorly maintained welder. Even under the best of circumstances however, given that many welding systems are operating in an isolated manner, diagnostic information relating to the health of these systems is often not reported or discovered until after a breakdown occurs. Other challenges relating to conventional welding systems also existed.
Many of these challenges are addressed in U.S. Pat. Nos. 6,486,439 and 6,624,388, which are incorporated herein by reference. These two patents disclose a welding and network information system wherein one or more welders can be controlled and/or monitored at a remote location. U.S. Pat. No. 6,624,388 discloses a system and method that includes a welder operatively coupled to a server and a network interface to enable a network architecture to communicate with at least one remote system. The remote system includes at least one remote interface to communicate with the network architecture, wherein the remote system accesses at least one HTTP socket to establish web communications with the welder and loads at least one application from the welder. The remote system accesses at least one Welding Application socket via the at least one application to exchange information between the welder and the remote system, wherein the at least one application includes at least one of a weld configuration component, a weld monitoring component, and a weld control component to interact with the distributed welding system. The network architecture disclosed in the '388 patent provides a structure, protocol and remote communications interface between welders, and/or other remote systems, across internal networks and/or to broader networks such as the Internet. These systems can include machinery in a plant production line, supervisory systems, inventory systems, quality control systems and maintenance systems associated with the welders. Communications between these systems facilitate such activities as electronic commerce, distributed control, maintenance, customer support, and order/supply/distribution of welding materials. Thus, the networked and distributed welding architecture disclosed in the '388 patent promotes a higher-level integration to achieve improved quality, productivity, and lower cost manufacturing. The '439 patent discloses welding and network information system that includes a welder operatively coupled to a server and a network interface to enable a network architecture to communicate with at least one remote system, wherein the remote system includes at least one remote interface to communicate with the network architecture and provide welding information to a user. The remote system accesses at least one HTTP socket to establish web communications with the welder and loads at least one application from the welder. The remote system accesses at least one Welding Application socket via the at least one application to exchange information between the welder and the remote system. The at least one application includes at least one welding information broker to determine whether the welding information in a local database is to be updated, the user receives the welding information via the remote interface and the local database or the remote interface and the network. As such, the '439 patent discloses a system that enables automated order and fulfillment of items such as replacement parts and/or welding programs and procedures.
Although the '439 patent and '388 patent significantly enhance the operation of multiple welders via a network, these patents do not address the power consumption of a plurality of welders to enable an operator to control and/or reduce the energy costs associated with the operation of such welders. Due to the increased energy costs, there is an unsolved need for an improved welding architecture to facilitate the monitoring and/or control of multiple welding systems to reduce the energy cost associated with the operation of such welders.